(88c) CFD-Modeling of LNG Dispersion Experiments

The CFD-tool FLACS was developed from 1980 to model hydrocarbon gas explosions in process facilities. To predict the gas build-up, the functionality has been extended to include dispersion. Extensive validation against experiments has been given high priority in the FLACS development. With support from Norsk Hydro, Total, Statoil and PTIL, and in cooperation with DNV, a LNG-development and validation project for FLACS was carried out. The first phase of the project was a validation activity in which 8 tests from Burro and 3 tests from Coyote experiments performed at China Lake (USA), and 4 tests from Maplin Sands (UK) have been simulated. Simulated downwind maximum gas concentrations at various distances have been compared to experiments showing good correlation, and this validation exercise will be presented. Models have been further developed to extend the pool modeling capabilities to allow the formation and spread of a pool with local evaporation rates based on heat from ground, wind speed, local vapor pressure. These models will be described, and simulation examples will be shown. The combination of a good description of physical models and the ability to take into account buildings, terrain or process plants is essential for a proper consequence modeling of LNG-releases.

References:

1 Steven R. Hanna, Olav R. Hansen, Seshu Dharmavaram, FLACS CFD air quality model performance evaluation with Kit Fox, MUST, Prairie Grass, and EMU observations, Journal of Atmospheric Environment, Volume 38 (2004) pages 4675-4687. 2 S.Dharmavaram, S.R.Hanna and O.R.Hansen, Consequence Analysis - Using a CFD Model for Industrial Sites, Process Safety Progress (Vol 24, No 4), pp 316-327, December 2005 3 Won K. Kim and Hans-Christen Salvesen, A Study for Prevention of Unconfined Vapor Cloud Explosion from Spilled LNG Confined in Dike, CCPS Conference Proceedings, Jacksonville Florida, 2002